Pulse or digital communications – Testing – Signal noise
Reexamination Certificate
1997-12-24
2001-05-08
Pham, Chi (Department: 2631)
Pulse or digital communications
Testing
Signal noise
C702S069000
Reexamination Certificate
active
06229847
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to measurement of the signal-to-noise ratio of communications signals. More specifically, but without limitation thereto, the present invention relates to a device for finding the signal-to-noise ratio of a constant envelope amplitude communications signal having a known modulation scheme.
Current techniques for measuring signal-to-noise ratio require extracting information from the signal, such as bit error rate devices. Examples of such devices may be found, for example, in U.S. Pat. No. 5.440,582 issued on Aug. 8, 1995 to Birchler et al. This device estimates signal quality from a stream of demodulated information extracted from the received signal. U.S. Pat. No. 4,835,790 issued on May 30, 1989 to Yoshida et al. discloses a specially clocked analog-to-digital converter to estimate the quality of a phase-shift keyed signal. U.S. Pat. No. 3,350,643 discloses a device that processes a stream of demodulated data from a digitally encoded transmission to estimate signal quality.
A continued need exists for a device that can find signal-to-noise ratio of a communications signal without the difficulty of having to first extract the transmitted information from the received signal.
SUMMARY OF THE INVENTION
A signal quality measurement device of the present invention is directed to overcoming the problems described above, and may provide further related advantages. No embodiment of the present invention described herein shall preclude other embodiments or advantages that may exist or become obvious to those skilled in the art.
A signal quality measurement device of the present invention comprises a deviation function for determining a measured deviation value from envelope amplitude samples of a communications signal and a table function of deviation values versus signal-to-noise ratios computed from a statistical model of atmospheric noise for finding a signal-to-noise ratio that corresponds to the measured deviation value.
An advantage of the signal quality measurement device of the present invention is that extraction of information conveyed by the communications signal is unnecessary, avoiding the need for decryption devices for encrypted data.
Another advantage is that signal-to-noise ratio may be estimated with very few components.
The features and advantages summarized above in addition to other aspects of the present invention will become more apparent from the description, presented in conjunction with the following drawings.
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Fendelman Harvey
Kagan Michael A.
Pham Chi
The United States of America as represented by the Secretary of
Tran Khai
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